package utils

import (
	"bytes"
	"fmt"
	"io/ioutil"
	"net"
	"runtime"
	"sync"
	"time"

	"golang.org/x/text/encoding/simplifiedchinese"
)

var (
	dunno     = []byte("???")
	centerDot = []byte("·")
	dot       = []byte(".")
	slash     = []byte("/")
)

type Charset string

const (
	UTF8    = Charset("UTF-8")
	GB18030 = Charset("GB18030")
)

// ConvertByte2String 转换编码
func ConvertByte2String(byte []byte, charset Charset) string {
	var str string
	switch charset {
	case GB18030:
		var decodeBytes, _ = simplifiedchinese.GB18030.NewDecoder().Bytes(byte)
		str = string(decodeBytes)
	case UTF8:
		fallthrough
	default:
		str = string(byte)
	}
	return str
}

// CheckNetwork 检测网络联通
func CheckNetwork() error {
	_, err := net.DialTimeout("tcp", "www.baidu.com:443", time.Second*6)
	if err != nil {
		return fmt.Errorf("network unreachable, error: %v", err)
	}
	return nil
}

// SyncMapLen 获取map元素个数
func SyncMapLen(m *sync.Map) int {
	cnt := 0
	m.Range(func(_, _ interface{}) bool {
		cnt++
		return true
	})
	return cnt
}

// CurrentTimeMillis / 获取当前毫秒数
func CurrentTimeMillis() int64 {
	return time.Now().UnixNano() / 1e6
}

// StackForStr 获取堆栈
func StackForStr(skip int) string {
	bts := Stack(skip + 1)
	return string(bts)
}

// Stack 获取堆栈
func Stack(skip int) []byte {

	skip += 1

	buf := new(bytes.Buffer) // the returned data
	// As we loop, we open files and read them. These variables record the currently
	// loaded file.
	var lines [][]byte
	var lastFile string
	for i := skip; ; i++ { // Skip the expected number of frames
		pc, file, line, ok := runtime.Caller(i)
		if !ok {
			break
		}
		// Print this much at least.  If we can't find the source, it won't show.
		_, _ = fmt.Fprintf(buf, "%s:%d (0x%x)\n", file, line, pc)
		if file != lastFile {
			data, err := ioutil.ReadFile(file)
			if err != nil {
				continue
			}
			lines = bytes.Split(data, []byte{'\n'})
			lastFile = file
		}
		_, _ = fmt.Fprintf(buf, "\t%s: %s\n", function(pc), source(lines, line))
	}
	return buf.Bytes()
}

// source returns a space-trimmed slice of the n'th line.
func source(lines [][]byte, n int) []byte {
	n-- // in Stack trace, lines are 1-indexed but our array is 0-indexed
	if n < 0 || n >= len(lines) {
		return dunno
	}
	return bytes.TrimSpace(lines[n])
}

// function returns, if possible, the name of the function containing the PC.
func function(pc uintptr) []byte {
	fn := runtime.FuncForPC(pc)
	if fn == nil {
		return dunno
	}
	name := []byte(fn.Name())
	// The name includes the path name to the package, which is unnecessary
	// since the file name is already included.  Plus, it has center dots.
	// That is, we see
	//	runtime/debug.*T·ptrmethod
	// and want
	//	*T.ptrmethod
	// Also the package path might contain dot (e.g. code.google.com/...),
	// so first eliminate the path prefix
	if lastSlash := bytes.LastIndex(name, slash); lastSlash >= 0 {
		name = name[lastSlash+1:]
	}
	if period := bytes.Index(name, dot); period >= 0 {
		name = name[period+1:]
	}
	name = bytes.Replace(name, centerDot, dot, -1)
	return name
}
